Reserve pressure tank system



Dec. 27, 1932. c, sANbERs' 1,892,535

RESERVE PRESSURE TANK SYSTEM Filed Dec. 31, 1930 2 Sheets-Shet 1 N f venl'all Cdr/ Qj dn j Dec. 27, 1932.

c. SANDERS RESERVE PRESSURE TANK SYSTEM Filed Dec. 51, 1930 2 Sheets-Sheet *2 Iq very (-01- Cdr/ ddqa er;

Patented Dec. 27, 1932 UNITED STATES- PATENT OFFICE CARL SANDERS, OF DETROIT, MICHIGAN, ASSIGNOR TO BINKS MANUFACTURING 00., OF CHICAGO, ILLINOIS, A CORPORATION OF DELAWARE RESITRVE PRESSURE TANK SYSTEM Application filed December 31, 1930. Serial No. 505,746.

My invention relates to liquid distribution systems in which the liquid is forced through piping to its points of use by the pressure of air on the liquid in a tank or other container.

In some of its general objects, my invention aims to provide a simple and easily installed liquid distribution system of this class which nections speedily whenever the main liquid (under the needed pressure) at the points of use during the refilling (and if necessary, the draining and cleaning) of the main tank from which the liquid is supplied; which will enable even inexperienced operators to make the necessary changes in the operative connections speedily whenever th main liquid tank needs to be refilled and to restore the normal connections after such refilling.

In some further aspects, my invention aims to provide simple and suitable provisions in such a liquid distribution for reducing the chances of having liquid forced into air supply pipes, which will entrap any liquid thus forced to an undue extent into the a r supply pipes under certain operative conditlons, and

which will prevent a damage in case air is supplied to the system under too high a pressure.

Moreover, my invention aims to provide simple and easily manipulated provisions whereby the residual liquid, left in the pipe system when its operation is discontinued, may be returned to the supply tanks; whereby the pipe system can thereafter be cleared of any deposits formed in it, and whereby the cleaning liquid employed for this purpose can readily be collected so as to be used again.

In large installations for the spray-painting of objectsas for example, in the plants of automobile inanufacturers-it is customary to have the spray-painting conducted in a large numberof spray booths, each of which require a supply of the liquid coating material under pressure. \Vhile this can be done by installing a separate liquid tank and air compressor adjacent to each spray booth, it has been found more economical and advantageous to supply the needed liquid coating material for a large number of spray booths (when these simultaneously require the same However, when a single source of supply is thus used in connection with a number of spray booths, the work in all of these booths would be interrupted whenever the single supply tank needs to be refilled, or cleaned, or both. And in practice such a refilling cannot always be done after working hours or during noon interruptions, particularly when demands on the plant require overtime or even 24 hour continuous operation, or where a greater amount of material is consumed in a shift than the actual tank contents.

On the other hand, the installing of a duplicate main liquid supply tank or socalled pressure tank would involve an undesirably high cost for this duplicate pressure tank, would increase the fire hazard due to larger storage of material, and also would require the watching and refilling of two main pressure tanks as contemplated by my system.

My present invention aims to reduce the cost of the needed equipment and to avoid any waste of time by the operators of the spray appliances by providing a liquid distribution system in which the coating material (or other liquid) normally flows from the main supply tank through a relatively small (and hence comparatively inexpensive) auxiliary or reserve tank, which reserve tank is normally filled with liquid and is of ample capacity for continuing the needed supply while the main tank is being refilled.

Moreover, my invention provides a simple arrangement for speedily disconnecting the main liquid supply tank operatively from uid distribution system of Fig. 1, showing the auxiliary tank and the supply of compressed air, for connecting the suppl of compressed air to the reserve tank to orce the stored liquid out of the reserve tank into the pipes leading to the spray booths, and for releasing the air pressure within the main supply tank so that both the head and the filler plug of the latter tank can readily be detached.

So also, my invention aims to provide arrangements whereby the residual liquid left in the piping at the end of the working period can readily be returned to the supply tanks, and, wherebythe contents of the reserve tank also can readily be forcedback into the main tank, so as to permit an expeditious cleaning of the auxiliary or reserve tank.

Still further and also more detailed objects, including the providing of some important safety features, will appear from the following specification and from the accompanyingdrawings, in which F i 1 is an elevation of portions of a liquid distrlbution system embodying my invention. with certain valves disposed for maintaining the supply of liquid from the main tank through the reserve tank to the supply piping.

Fig. 2 is an enlarged elevation of the auxlliary tank and adjacent portions of the liqthe interconnected air and liquid valves as they are disposed when the main tank is disconnectedand the liquid is being supplied .to the pipe system through the auxiliary tank.

Fig. 3 is an enlargement of an upper portion of Fig. 1.

Fig. '4 is an enlarged vertical section through the three-way valve 14 of Fig. 1 and parts of the piping connected by this valve; the section being taken in the plane of the drawing of Fig. 1, with the valve.

In the illustrated embodiment, the main liquid material tank is of a common fpressure tank type in which clamps 2 hold the cover or head 3 in sealing relation to the body 1 of the tank. This head desirably carries an air-driven motor 4 for rotating an agitator within the tank, which agitator preferably includes blades or vanes 5 disposed hoth near the bottom of the tank body and'intermediate of the height of the tank body.

The auxiliary or reserve tank, which may be of muchsmaller capacity 'than the main tank is disposed so that the top of its head 6A is at a lower level than the bottom of the main tank; and when my liquid distribution system is used in connection with some materials, the head GA on the body 6 of the auxiliary tank also carries an air motor 4 driving an agitator having blades 5 (Fig. 2) disposed within the body of the tank. Connecting the two tanks is a connecting pipe 7 which preferably extends almost to the bottom of the secondary tank, the flow through this connecting pipe being'icontrolled by a valve 8.

The compressed air for propelling the liquid material is supplied through an air 1nlet pipe 9 controlled by a hand valve 10 and through a pressure regulator 11 to the upper portion of a trap 12. Leading from the upper portion of this trap, which is disposed at a higher level than the top of the shown in dotted lines in Fig. 4), or to shut oil the said connection to the main tank while connecting the air pipe 13 with the air outlet 14A of the three-Way valve as shown in full lines in Fig. 4.

Mounted in the U-shaped air pipe portion 13, desirably near to the liquid material valve 8 is a valve 16. The cocks or movable portions 30 of the two valves 8 and 16 carry handles 8A and 16A respectively), which handles are, connected by a link 17 so that the two valves can be opened simultaneously by a movement of this link in one direction, or closed simultaneously by moving the link in the opposite direction.

The upper portion of the trap 12, to which air is supplied under pressure by the air inlet pipe 9, is also connected to a second air pipe 18 which leads downward into the top of the secondary tank. For the agitator motors associated with each tank, the needed actuating air is, supplied through pipes 19, each controlled by a valve 20, the supply of this air being; independent of the control of the air which is supplied through the inlet pipe 9 and distributed through the trap 12 and the pipes 13 and 18 to the upper portions of the main tank and the auxiliary tank.

Leading from the auxiliary tank is a liquid distribution pipe 21, which extends almost to the bottom of this tank as shown in Fig. 2, and from which pipe 21 the needed branch pipes 22 extend respectively to the spray appliances (not here illustrated) for which the liquid material is being supplied. The flow through this liquid distribution pipe 21 can be controlled by a hand valve 34 disposed between the auxiliary tank and the nearest one of the branch pipes, and another hand valve 23 disposed near the farther end of the pipe 21 controls the discharge of liquid from the end of that pipe.

When the above described liquid distribution system is to be used, the actuating link 17 for the valves 16 and 8 is disposed as shown in Fig. 1, so that the two tanks are measa'u connected, and the handle 15 of the valve 14 is initially turned up (as in Fig. 4) so as to vent the top of the main tank to the outer air,

the air'inlet valve 10 being closed. When the main tank is then filled for the major portion of the height of its container, as for example to the upper level U indicated in Fig. 1, liquid also passes through the tank-connecting liquid duct 7 to the auxiliary tank, thereby filling the auxiliary tank completely and filling both the liquid distribution pipe 21 and the air pipe 18 up to the same level U to which the main tank is filled.

Then the handle 15 of the three-way valve 14 is turned back to the down position shown in F ig. 1, so as to connect the air pipe 13 with the upper portion of the main tank, before the compressed air is admitted to the system by opening the inlet valve 10. When this air inlet valve is then opened, the compressed air presses down equally on the liquid in the main tank and (through the liquid in the air pipe 18) on the liquid in the auxiliary tank, thereby forcing liquid out of the auxiliary tank into the liquid-distribution pipe system as soon as the valve 34 is opened, and correspondingly lowering the upper level U of the entire supply of liquid.

In doing this, the major portion of the liquid is drawn from the main tank (since this is of much greater bore than the air pipe 1.8) and has already been stirred by the agitator blades 5 in the main tank. At the same time, with air admitted to the agitator motors through the pipes 19, the liquid in the auxiliary tank is also stirred up by the agitators 5 in the secondary tank, so as to insure a uniform consistency of the liquid forced into the main distribution pipe 21.

With the auxiliary tank disposed entirely below the connecting liquid duct 7, the supply of liquid to the distribution pipes can be continued uninterruptedly until the main tank is substantially emptied; and, since the main distribution pipe 21 has its inlet near the bottom of the auxiliary tank, this uninterrupted supply of liquid can be continued until the auxiliary tank also is substantially emptied, without interrupting the supply of liquid to the distribution piping. The secondary tank thus constitutes both an auxiliary receptacle for initially storin considerable liquid in addition to the capaclty of the main tank, and also forms a receptacle through which the liquid from the main tank passes through the liquid distribution pipe and from the latter to the branch or consumption pipes 22. 3

However, when the level of liquid in the main tank is relatively low, as shown b opening gage cocks 24: on this tank, the attendant moves the valve-operating link 17 to the position shown in Fig. 2 (thereby closing both of the valves 16 and '17 and also moves the handle of the three-way valve 14 so as to open the connection through the last named valve from the upper portionof the main tank to the outer air so as to permit the air within the main tank to drop to atmospheric pressure. With the pressure in the main tank thus reduced, this tank then can readily be refilled with a fresh supply of liquid. 1

During this refilling, the downward pressure of the compressed air in the air pipe 18 forces the liquid out of this pipe downward so as to empty this pipe of liquid, and then begins to fill the secondary tank with compressed air while forcing the liquid out of the tank into the liquid supplypipe 21. Since this pipe 21 has its inlet near the bottom of the secondary tank (as shown in Fig. 2), this tank also can be almost entirely emptied, thereby maintaining an uninterrupted supply to the pipe 21 and the branch or consumptiqlii pipes 32 during the refilling of the main ta Moreover, while liquid is thus being supplied from the secondary tank, any sediment in the main tank can be drawn oil by temporarily removing the usual drain plug 25 at the bottom of this tank, and the main tank can be cleaned in the usual manner if this seems necessary. I

When the demand for a supply of the liquid is halted-as for example at the end of the working daythe air inlet valve 10 is closed first, thereby discontinuing the supply of compressed air to both tanks, and the handle 15 of the three-way valve is turned to the position shown in full lines in Fig. 4, so as to provide an air vent for reducing the air pressure above the liquid in the main tank to atmospheric pressure. An auxiliary hose 36 connected to a supply of-compressed air is then connected to the farther end of the main liquid distribution pipe 21 (as shown in dotted lines in Fig. 1), after which the valve 23 is opened. The air thus supplied through this hose will blow all of the liquid out of the main liquid pipe 21 back into the secondary tank; and if the valves 25 in the branch pipes are opened one by one, the liquid in these branch pipes can likewise be blown back through the liquid pipe 21 and into the auxiliary tank by connecting a compressedair hose successively to the outlets of each of these branch pipes.

In practice, this returning of liquid may be continued only until the distribut on pipes are cleared of liquid, thereby avoiding any gradual hardening of liquid in these pipes. However, the supply of compressed air through the auxiliary hose 36 and the main y liquid pipe 21 may be continued until the auxiliary tank also is substantially emptied,

namely to the level of the lower end of the connecting pipe 7. After the liquid contents of the distribution pipes and the auxiliary tank have thus been blown back into the main tank, air will be forced through the auxiliary tank and the said connecting pipe into the main tank, and the Vibration due to the bubbling of this air through the liquid in the main tank will inform the attendant that the auxiliary tank is emptied.

The valve 23 is next closed, as also the valve 8, thereby disconnecting the auxiliary tank both from the main tank and from the supply of compressed air. The air pressure in both the auxiliary tank and the liquid pipes can then be released in the usual manner, as by removing the filler plug 38 on this tank, after which the auxiliary tank and the pipe system can readily be cleaned in the following manner:

The liquid still remaining in the bottom of the auxiliary tank is first drained off after removing the drain plug 39, and this plug is replaced. Next, the auxiliary tank is filled through the filler opening with a quantity of a cleaning liquid proportion-ed to the lengths of the liquid distribution pipe and its branches, and the filler plug is replaced. Vith the valve 34 still open, the air inlet valve 10 is then opened so as to subject the cleaning liquid to air pressure. Then the valves 31 and 23 in the pipe system are opened, thereby permitting the cleaning liquid to be forced by. the air pressure through the main liquid distribution pipe 23 and through a hose 28 into a collecting can/29 for repeated use. Likewise, if the pipe-end valve 23 is cl sed and each of the valves 35 in the branch pipes is opened successively, the cleaning liquid can similarly be forced through each of these branch pipes 22.

After the branch pipes have thus been cleaned also, the supply of compressed air to the. secondary tank is continued (with the valve :23 o Jen) until all of the cleaning liquid has been blown out of the secondary tank and the piping. This leaves the piping filled with air until the system is to be used again, when it is restarted as previously explained. If air should be admitted during the use of my system toeither the main or, the

auxiliary tank at an excessive pressure-as might happen if the pressure gauge 11 was not properly adjusted or did not function properly the undue pressure would be apt to cause a leakage between the bodies and the heads of the tanks. To safeguard against this, it is usually customary to mount a suitably adjusted pop valve on the head of each tank. but pop valves so disposed in my system would be inoperative, since they would be below the upper level of the liquid and hence would fill with liquid. I therefore connect a suitable relief valve (such as a so-called pop valve) to the air supply system ad acent to the trap 12 where it will continuously be above the upper level of the liquid. For example, I may mount this relief valve 2t on a horizontal pipe 27 connecting the air pipe 18 with the trap, where it will be operatively connected also by the upper portion of the trap with the air supply pipe 13 leading to p the main tank.

However, while I have heretofore described myinvention in connection with an embodiment including numerous desirable details of construction and arrangement, I do not wish to be limited in these respects, since many changes might be made without departing either from the spirit of my invention or from the appended claims. Nor do I Wish to be limited to the use of my system in connection with the supply and distribution of liquid coating materials, or to the above described particular manipulation of its various parts.

Fez-example, when my system is used for distributing liquids having no ingredients that are likely to settle by gravity, the agitating means in the auxiliary tank (and for some liquids also in the main tank) may be omitted. On the other hand, with pigmentcarrying liquids, the double agitation secured by my two-tank arrangen'ient is of decided advantage for securing a coating of high uniformity even with a quite finely atomized spray, I

In addition to confining the supply of liquid to one locality, thereby permitting it to be in a tire-proof room distant from the points at which the liquid is used, my system also avoids the labor of transportation and filling, together with the losses in spilling, which would occur when supplies of the liquid are taken to many separated polnts. So also, since the supply of liquid of any particular color can all be stored at the plant in one tank, the ditficulty of matching colors at different points is eliminated.

\Vhat is more, my system can be used advantageously for supplying liquids through pipe lines of large lengths, by employing a suitable air pressure to both tanks, this system having been used successfully in connection with liquid coating materials in plants requiring distances of over a quarter of a mile between the auxiliary tank and the most distant spray booths. I

I claim as my invention:

1. A liquid supply system comprising a main liquid tank, an auxiliary liquid tank disposed at a lower level than the main tank, a connecting duct leading from the lower portion of the main tank to the lower portion of the auxiliary tank, a liquid distribution pipe leading from the lower portion of the auxiliary tank, a liquid trap disposed at a higher elevation than the top of the main tank, a main air-supply pipe leading to the upper portion of the trap, a first air pipe leading from the upper portion of the trap to the upper portion of the main tank, and a second air pipe leading'from the upper portion of the trap downwardly to the upper portion of the auxiliary tank.

2. A liquid supply system as per claim 1,

including a pressure-relief valve operatively connected to the upper portion of the trap.

3. A liquid supply system as per claim 1, including a pressure-relief valve operatively connected to one of the air pipes at a higher elevation than the top of the main tank.

4. A liquid supply system comprising a main liquid tank, an auxiliary liquid tank disposed at a lower level than the main tank, a

connecting duct leading from the lower portion of the main tank downward into the auxiliary tank; air-supply means for supplying air under equal pressures to the upper portions of both tanks; and a liquid-distributi on pipe system including an inlet pipe leading from the auxiliary tank near the bottom of that tank; the total liquid capacity of the auxiliary tank and the said liquid-distribution pipe system be ng not greater than the liquid capacity of the main tank; and a connection to the pipe system adjacent to its outlet end whereby air may be blown into the said system to force the liquid contents of this pipe system and of the auxiliary tank into the main tank.

5. Aliquid supply system comprising a main liquid tank an auxiliary liquid tank disposed at a lower level than the main tank, a connecting duct leading from the lower portion of the main tank downward into the auxiliary tank; air-supply means for supplying air under equal pressures to the upper portions of both tanks; a liquid-distribution pipe system including an inlet pipe leading from the auxiliary tank near the bottom of the tank; means for simultaneously closing the connecting duct and shutting off the said supply of air to both tanks; and means for ventingjthe top of the main tank, and together wit-h a connection adjacent to the outlet end of the said pipe system for attachment to a supply of compressed air, the venting means and the said connection cooperating to permit the liquid contents of both the pipe system and the auxiliary tank to be blown back into the main tank.

6. A liquid supply system comprising a main liquid tank, an auxiliary liquid tank disposed at a lower level than the main tank, a connecting duct leading from the lower portion of the main tank to the lower portion of {the auxiliary tank,a liquid distribution pipe leading from the lower portion of the auxiliary tank; acompressed-air supply pipe leading to the upper portion of the main tank and including a U-shaped pipe portion disposed adjacent to the said connecting duct, an air-control valve in the said adjacent pipe portion, a valve controlling the flow of liquid through the said duct, and means connecting the two valves for simultaneously opening or closing both valves.

disposed at a lower level than the main tank,

aconnecting duct leading from the lower portion of the main tankto the lower portion of the auxiliary tank, a liquid distribution pipe leading from the lower portion of the auxiliary tank; and air-supply means for supplying air under equal pressure to the upper portions of both tanks; the air-supply means including a first air pipe having its outlet through the top of the main-tank, a second air pipe leading downwardly through the top of the auxiliary tank, and an air supply inlet connected to both of the air pipes at a higher elevation than the top of the main tank; a liquid valve in the connecting duct, an air control valve in the first air pipe, and means connecting the two valves for simultaneously opening or closing both valves.

8. A liquid supply system as per claim 7, including means for selectively connecting the first air pipe either with the upper portion'of the main tank or with the outer air.

9. A liquid supply system comprising a main liquid tank, an auxiliary liquid tank disposed at a lower level than the main tank, a connecting duct leading from the lower portion of the main tank to the lower portion of the auxiliary tank, a liquid distribution pipe leading from the lower portion ofthe auxiliary tank; air-supply means for supplying air under equal pressure to the upper portions of both tanks, the air-supply means comprising air pipes extending downward from an air-supply inlet disposed at higher elevation than the top of the main tank respectively into the main tank and the'auxiliary tank; and a three-way valve interposed in the air pipe leading to the main tank and normally affording a clear passage for air through the valve from the inlet to the main tank, the three-way valve including a valve member movable to a position in which it closes the said passage through the valve and affords an air gent for the upper portion of the main tan Signed at Detroit, Michigan, December 26th,1930.-.

CARL SANDERS.

CERTIFICATE OF CORRECTION. Patent No. 1,892, 5 5. December 27, 19 2} CARL SANDERS.

It is hereby certified that error appears in the printed specification. of the above numbered patent requiring correction as follows: Page-1, line 9, strike out -"nections speedily whenever the main" and insert instead the words will maintain a continuous supply of; line 16, for "th" read the and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office;

Signed and sealed this 15th day of September, A. D.- 1958.

Henry Van Arsdale (Seal) Acting Commissioner of Patents. 

